How to Get Correct Exposure in Photography | Exposure Triangle, Pt. 3
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Video: How to Get Correct Exposure in Photography | Exposure Triangle, Pt. 3
We’re continuing our series within a series to answer the age-old question: How do we get to the perfect exposure? In this article (the third of four), we’re going to look at how to use the histogram and highlight alert to maximize dynamic range. This information is crucial because getting the correct exposure will affect your image quality and control your flexibility in post-production.
If you missed the first two articles, we looked at the artistic components of the exposure triangle to show you how to use it to get correct exposure in photography and how it relates to composition in the real world; like part one and part two of this series, this article expands on concepts covered in our Photography 101 workshop.
Let’s dive in!
The Histogram for Post-Production
A histogram is a graph that reveals how much of your image is made up of shadows and highlights. In a histogram, the blacks and shadows occupy the left side of the graph, the midtones reside in the center, and the highlights and whites occupy the right side (along the X-axis). The Y-axis represents the amount of shadows or highlights in a given area of the frame. It’s worth getting to know your histogram as it represents a critical tool in your photography arsenal, both in-camera and during post-production.
How to Identify the Shadows, Midtones, and Highlights in a Histogram
For the image above, here is how the different zones of shadows and highlights can be analyzed.
As you can see the majority of the shadows can be found in the rocks on the lefthand side of the image, which is exactly where they show up on the histogram. Meanwhile, the ocean makes up the midtowns and the sky contains the highlights, again, just as they’re represented in the Histogram. These graphs will look different for each image, but the information breaks down the same way, and what it’s telling us is important to understand.
How Adjusting Exposure Affects the Histogram
As you decrease the exposure, you’ll see that the information represented in the histogram will shift to the left. Likewise, if you increase the exposure, you’ll notice that the information on the graph shifts to the right side of the histogram.
[Related Reading: How We Shot It | Maximizing Dynamic Range on a Cloudy Day]
How to Use the Histogram to Maximize Dynamic Range
When we talk about maximizing dynamic range, what we mean is keeping as many shadow and highlight details as possible. As I mentioned above, adjusting your exposure up or down will move the shadow and highlight details to the right or left. In order to maximize dynamic range, adjust your exposure so that the the shadows and highlights move as close to the center as possible. You don’t want to push too far in either direction and “clip” either the shadows or highlights because that would mean you no longer have detail wherever clipping occurs (see the image below).
How to Process an Image with a Lighting-Based Preset
The reason we want to maximize our dynamic range is that it simplifies the development or post-production process. We’re going to use a Visual Flow preset (Crush Pack > HDR) to illustrate what I’m talking about.
With one click (and a couple quick adjustments to exposure and contrast), you can see how well the preset was able to lift the shadows and and maintain the highlights to retain a ton of detail. The results wouldn’t be as remarkable if we hadn’t maximized the dynamic range in the original RAW file. All the information we needed for a stellar edit was already present within the file.
In addition to the slider adjustments featured in the image above, we also adjusted the tone curve. The reason we did this is because dropping the highlights and whites and raising the shadows and blacks results in a very flat image. By adding tone curve adjustments, we’re able to bump up the contrast and create a more dynamic image (see below).
[Related Reading: When Should You Blow Out the Highlights?]
The Histogram In-Camera
It’s also important to understand how to use the histogram in-camera. It’s a tool I use for every shoot. I recommend that you figure out how to bring up the histogram on your particular camera model and make sure it’s visible when you’re shooting.
In-Camera Case Studies
Case Study #1
In the image above, you can see a lot of the area around the model is blanketed in shadows, which shows up as a spike in the shadows on the left side of the histogram. The results are to be expected as this scene features several dark components. The important highlights have been retained and do not appear to be clipped.
I say “important highlights” because the tiny fraction of highlights that have been clipped are located in the bright area in the top left of the frame as well as along part of the chair that the model is sitting on. What we don’t want are highlights being clipped on the model’s skin. One way we can verify whether or not we’ve retained the important highlights is by using the highlight alert.
The Highlight Alert
The highlight alert is an important that should be used in conjunction with the histogram. If any highlights are blown out, an enabled highlight alert will blink over the affected area (see the image below).
Pro Tip: Add the Highlight Alert as one of the items in your quick menu (if you have that option – be sure to check your camera manual if necessary) so that you can turn it on and off quickly as needed. Although you’ll want to enable the highlight alert while shooting, you may want to show your clients the images on the back of the camera at some point, and you don’t want to distract them with the blinking highlight alert.
Case Study #2
For this shot, the model was standing under hard light. The histogram reveals that most of the details were captured in the midtown range. There aren’t too many deep shadows or blown out highlights. This pattern on the histogram is quick and easy to read while out shooting in bright conditions.
Case Study #3
Unlike the image in Case Study #2, this histogram is a lot trickier to read. With the exception of a few highlights, most of the details are spiking in the shadows. If you don’t know what the histogram is telling you for this dramatically lit image, you might want to overexpose the image to balance out the graph. However, that would completely change the direction of this photo (see the image below).
The important thing here is we retained enough detail to have plenty of room to make adjustments in post. If you intend for the photo to be dark (or use low key lighting), then it’s okay for the details in the histogram to lean toward the darker side. Just remember to use the highlight alert to spot any small areas that might be clipped in the image.
Case Study #4
Sometimes, it’s okay to go the opposite direction of Case Study #3 and create a high key image, if that’s what’s intended. If the details in the image would prove more distracting than helpful for enhancing the image, feel free to blow out some of the highlights. That is what drove my decision to blow out the highlights in this image.
Case Study #5
For the above image, I used flash to simulate natural light in a jiu jitsu studio. Whenever you have a lot of white in your image, expect to see a spike on the highlight side of the histogram, which happened in this image. Reading the histogram alone would make it difficult to know whether or not I clipped any highlights, so it helps to use the highlight alert in these situations.
What Is the Proper Exposure?
As you can tell by the case studies above, intention plays a key role in determining the proper exposure for a give photograph. Some lean more toward the shadows while others favor blown out highlights. Still, your safe place for exposure is maintaining as much information in the image as you possible can.
Here’s a quick reference guide for different types of shots and what the exposure should look like:
- HDR imagery: Aim to retain as much image information as possible
- Dramatically lit imagery: Go with intention – if the image is meant to be dark, expose accordingly
- Bright & Airy or high key imagery: Again, go with intention – if the image is meant to be bright, it’s okay to blow out some of the highlights so long as they’re not over the subject’s skin
The Histogram in Lightroom Vs. In-Camera
You may have noticed that the histogram in Lightroom features a selection of colors while the histogram in the camera we used featured only a black & white graph. Some cameras may offer an RGB version of the histogram. Like the shadows and highlights, the various colors in a histogram represent where that color exists in the image and to what level of intensity.
We hope you enjoyed this video and lesson (the third of a four-part series) on using the histogram and highlight alert to get correct exposure in photography. In the next article, we’ll continue to revisit concepts from Photography 101 and work through the process of getting a correct exposure.
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